Hierarchical Design and Interfacial Work Function Modulation Endow Fe ₂ O ₃ /SnO ₂ /Carbon Foam Improved Sensibility for Rehabilitation Training

The escalating demands for continuous, accurate, and non-invasive monitoring of physiological motions in modern rehabilitation medicine have significantly propelled the development of high-performance flexible sensors with sufficient sensitivity to detect weak signals and suitable detection range to accommodate wide amplitudes. Herein, 3D Fe₂O₃/SnO₂/carbon foams (Fe₂O₃/SnO₂/CFs) with gradient microstructure and tunable interface work function are constructed. The n-n Fe₂O₃/SnO₂ heterojunction facilitates interfacial charge transfer, substantially reducing the initial resistance (R_0↓). Concurrently, within carbon foam, the vertically-grown hierarchical architectures composed of Fe₂O₃ micro-cones with gradient stiffness and surface-distributed SnO₂ nanoparticles synergistically generate stress concentration at Fe₂O₃ tips and the proliferation of conductive pathways upon compression, thereby amplifying resistance variation (ΔR_↑) for improved sensitivity and extended detection range. Capitalizing on these structural advantages, Fe₂O₃/SnO₂/CF-based flexible pressure sensor exhibits an elevated sensitivity of 479 kPa^-1, a wide sensing range of 0-50 kPa, and exceptional stability. Furthermore, smart insoles integrated with Fe₂O₃/SnO₂/CF sensors enable real-time gait analysis, demonstrating its capability to give guidance on personalized rehabilitation training and therapeutic management through precise assessments of neurological and traumatic disorders.